How Do You Troubleshoot Common Wifi Internet Issues
Understanding Network Addressing
When using the Internet, individuals are assigned either a Public IPv4 address, like “231.208.157.108”, or an IPv6 address, such as “2000:d2ac:3d24:2b2a:cbb7:3d:598c:c532”. It is possible to verify which address is assigned by visiting https://test-ipv6.com/. However, when attempting to communicate these addresses, it can become cumbersome, especially when dealing with MAC addresses, such as “21:aa:48:ca:73:3f”. Furthermore, this method does not provide historical data.
Navigating the World Wide Web
Accessing a website, like “https://toy.org”, initially involves interacting with a DNS server to translate the host portion (toy) combined with the Top Level Domain (org) of the URL to an IP address, such as “218.144.205.88”. Moreover, your computer and browser transmit their type with each web request, for example: Mozilla/5.0 (compatible; MSIE 9.0; AOL 9.7; AOLBuild 4343.19; Windows NT 6.1; WOW64; Trident/5.0; FunWebProducts)
Significance of Default Gateways
By default, your gateway is usually an address that is automatically configured via DHCP, resulting in a default gateway similar to “192.0.0.74”. For IPv6, further information can be found on how-to-fix-ipv6-connectivity/. Additionally, it is possible to check default gateways on Mac or Linux by using:
command-to-check
IPv4 Routes and the Host IPv4 Route Table (inc. VPN)
netstat -rn -f inet | egrep -i "default|0/1|128.0/1"
0/1 172.18.12.193 UGScg utun3 default 192.0.0.74 UGScg en0 128.0/1 172.18.12.193 UGSc utun3
Note: We are not just looking for the default but also for any VPN that overrides the public v4 address space.
IPv6 Routes and the Host IPv6 Route Table (inc. VPN)
netstat -rn -f inet6 | egrep -i "default|2000::/3"
If you have IPv6 active the above should return at least one route (as per below) via a known interface such as “en0 " on a Mac.
default fe80:71a:372f:488f:c93%en0 UGcg en0 default fe80::%utun0 UGcIg utun0 default fe80::%utun1 UGcIg utun1 default fe80::%utun2 UGcIg utun2 2000::/3 utun3 USc utun3
Note: We are not just looking for the default but also for any VPN that overrides the public v6 address space.
Debugging DHCP for both IPv4 and IPv6
To get a look at the low level DHCP configuration (Mac/Linux):
ipconfig getpacket en0
...
domain_name_server (ip_mult): {207.119.100.6, 34.95.4.217}
end (none):
...
So, in the above we are not getting IPv6 DNS servers from the DHCPv4 reply but…
ipconfig getv6packet en0
DHCPv6 REPLY (7) Transaction ID 0x80940b Length 76
Options[4] = {
CLIENTID (1) Length 14: DUID LLT HW 1 Time 668691856 Addr 21:aa:48:ca:73:3f
DNS_SERVERS (23) Length 32: 2606:4700:4700::1111, 2001:4860:4860::8844
DOMAIN_LIST (24) Length 0: Invalid
SERVERID (2) Length 10: DUID LL HW 1 Addr 39:f3:54:b2:1c:1a
}
Resolving Issues with Wired or Wireless Connections
When it comes to transferring data to your router, you may be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Actions to Take on Apple macOS / OSX System
Regardless of whether you are using OSX/macOS versions such as 10.13.9, 11.1.6, or 12.0.1, there are various troubleshooting tools available. However, these manual actions and scripts do not provide a set of correlated values over time. This is where the significance of automated remote troubleshooting comes into play, particularly for teams that adopt remote work and the concept of Work From Anywhere (WFA).
Utilizing Built-in Scripts for Assistance
On OSX/macOS, the sudo wdutil info tool is extremely useful as it provides a dump of current wireless settings to the CLI, and it can also be configured to generate specific logs for troubleshooting purposes. Additionally, the sysdiagnose tool offers a more comprehensive approach, as it can generate a wide range of logs, although most of these logs are point-in-time only in relation to wireless, similar to the wdutil tool.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will generate logs in /var/tmp/<blah>.tar.gz for you. If you prefer to run it interactively, you can use sudo /usr/bin/sysdiagnose, although it will issue a privacy warning. When not run in the background, it should open Finder in the correct location, or you can navigate to /var/tmp using Finder with Cmd+Shift+G. Keep in mind that the file sizes are approximately 300MB or slightly more.
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